Thin Film Transistor Array Panel and Method for Manufacturing the Same

ABSTRACT

The present invention provides a TFT array panel and a manufacturing method of the same, which has signal lines including a lower layer of an Al containing metal and an upper layer of a molybdenum alloy (Mo-alloy) comprising molybdenum (Mo) and at least one of niobium (Nb), vanadium (V), and titanium (Ti). Accordingly, undercut, overhang, and mouse bites which may arise in an etching process, are prevented, and TFT array panels that have signal lines having low resistivity and good contact characteristics are provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation application of co-pending U.S.application Ser. No. 11/180,989, filed Jul. 12, 2005, issued U.S. Pat.No. 7,301,170; which claims priority to and the benefit of Korean PatentApplication No. 10-2004-0071612 filed in the Korean IntellectualProperty Office, Republic of Korea, on Sep. 8, 2004, the contents ofwhich are all hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present description relates to a thin film transistor (TFT) arraypanel for a liquid crystal display (LCD) or an organic light emittingdisplay (OLED) and a manufacturing method for the same.

(b) Description of the Related Art

Liquid crystal displays (LCDs) are one of the most widely used flatpanel displays. An LCD includes a liquid crystal (LC) layer interposedbetween two panels provided with field-generating electrodes. The LCDdisplays images by applying voltages to the field-generating electrodesto generate an electric field in the LC layer that determinesorientations of LC molecules in the LC layer to adjust the polarizationof incident light.

An LCD including two panels provided with field-generating electrodesrespectively, wherein one panel has a plurality of pixel electrodes in amatrix and the other has a common electrode covering the entire surfaceof the panel, dominates the LCD market.

The LCD displays images by applying a different voltage to each pixelelectrode. For this purpose, thin film transistors (TFTs), having threeterminals to switch voltages applied to the pixel electrodes, areconnected to the pixel electrodes, and gate lines to transmit signalsfor controlling the thin film transistors and data lines to transmitvoltages applied to the pixel electrodes are formed on a thin filmtransistor array panel.

A TFT is a switching element for transmitting the image signals from thedata wire to the pixel electrode in response to the scanning signalsfrom the gate wire.

The TFT is applied to an active matrix organic light emitting display asa switching element for controlling respective light emitting elements.

Meanwhile, chromium (Cr) is conventionally the predominant material usedfor the gate line and the data line of a TFT array panel. However, Crincludes the drawbacks of high stress and resistivity.

Considering the trend of increasing LCD size, a material having lowresistivity is urgently required since the lengths of the gate and datalines increase along with the LCD size. Accordingly, Cr is notappropriate for use in a large size LCD.

Aluminum (Al) is a well known material as a substitution for Cr due toits low resistivity. However, Al also has drawbacks including hillockgrowth that may be induced by high temperature, Al may be diffused intoa semiconductor when Al contacts the semiconductor, and, since Al haspoor contact characteristics with pixel electrode materials, such asindium tin oxide (ITO), a poor contact between a drain electrode of Aland a pixel electrode of ITO may occur.

SUMMARY OF THE INVENTION

It is an object of the present invention to solve the above-mentionedproblems and to provide a thin film transistor array panel with signallines having low resistivity and good contact characteristics withoutsuch problems.

To achieve the object, the present invention provides a thin filmtransistor array panel having gate lines and data lines formed ofmolybdenum alloy (Mo-alloy), which is composed of Mo and at least one ofniobium (Nb), vanadium (V), and titanium (Ti), and has low resistivityand good chemical resistance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a layout view of a TFT array panel for an LCD according to anembodiment of the present invention;

FIG. 2 is a sectional view of the TFT array panel shown in FIG. 1 takenalong the line II-II;

FIGS. 3A, 4A, 5A, and 6A are layout views sequentially illustrating theintermediate steps of a method of manufacturing a TFT array panel for anLCD according to the embodiment of FIGS. 1 and 2;

FIG. 3B is a sectional view of the TFT array panel shown in FIG. 3Ataken along the line IIIb-IIIb′;

FIG. 4B is a sectional view of the TFT array panel shown in FIG. 4Ataken along the line IVb-IVb′ in the step following the step shown inFIG. 3B;

FIG. 5B is a sectional view of the TFT array panel shown in FIG. 5Ataken along the line Vb-Vb′ in the step following the step shown in FIG.4B;

FIG. 6B is a sectional view of the TFT array panel shown in FIG. 6Ataken along the line VIb-VIb′ in the step following the step shown inFIG. 5B;

FIG. 7 is a layout view of a TFT array panel for an LCD according toanother embodiment of the present invention;

FIG. 8 is a sectional view of the TFT array panel shown in FIG. 7 takenalong the line VIII-VIII′;

FIGS. 9A to 13B are sectional views of the TFT array panel shown inFIGS. 7 and 8 in intermediate steps of a manufacturing method accordingto an embodiment of the present invention;

FIG. 14A is a layout view of a TFT array panel for an LCD according toanother embodiment of the present invention;

FIG. 14B is a sectional view of the TFT array panel shown in FIG. 14Ataken along the line XIVB-XIVB′;

FIGS. 15A to 16B are sectional views of the TFT array panel shown inFIGS. 14A and 14B in intermediate steps of a manufacturing methodaccording to an embodiment of the present invention;

FIG. 17 is a layout view of a TFT array panel for an LCD according toanother embodiment of the present invention;

FIGS. 18 and 19 are sectional views of the TFT array panel shown in FIG.17 taken along the line XVIII-XVIII′ and the line XIX-XIX′,respectively;

FIGS. 20 and 21 are sectional views of the TFT array panel shown in FIG.17 taken along the line XX-XX′ and the line XXI-XXI′, respectively;

FIGS. 22, 24, 26, 28, 30, 32, and 34 are layout views of the TFT arraypanel shown in FIGS. 17 to 21 in intermediate steps of a manufacturingmethod according to an embodiment of the present invention;

FIGS. 23A, 23B, and 23C are sectional views of the TFT array panel shownin FIG. 22 taken along the lines XXIIIa-XXIIIa′, XXIIIb-XXIIIb′, andXXIIIc-XXIIIc′;

FIGS. 25A, 25B, and 25C are sectional views of the TFT array panel shownin FIG. 24 taken along the lines XXVa-XXVa′, XXVb-XXVb′, and XXVc-XXVc′;

FIGS. 27A, 27B, 27C, and 27D are sectional views of the TFT array panelshown in FIG. 26 taken along the lines XXVIIa-XXVIIa′, XXVllb-XXVIIb′,XXVIIc-XXVIIc′, and XXVlId-XXVId′;

FIGS. 29A, 29B, 29C, and 29D are sectional views of the TFT array panelshown in FIG. 28 taken along the lines XXIXa-XXIXa′, XXIXb-XXIXb′,XXIXc-XXIXc′, and XXIXd-XXIXd′;

FIGS. 31A, 31B, 31C, and 31D are sectional views of the TFT array panelshown in FIG. 30 taken along the lines XXXIa-XXXIa′, XXXIb-XXXIb′,XXXIc-XXXIc′, and XXXId-XXXId′;

FIGS. 33A and 33B are sectional views of the TFT array panel shown inFIG. 32 taken along the lines XXXIIIa-XXXIIIa′ and XXXIIIb-XXXIIIb′;

FIGS. 35 and 36 are sectional views of the TFT array panel shown in FIG.34 taken along the lines XXXV-XXXV′ and XXXVI-XXXVI′;

FIG. 37 is a graph illustrating variation of resistivity according todeposition pressure of Mo—Nb,

FIG. 38 is a graph illustrating variation of resistivity according tothe included amount of Nb;

FIG. 39 is a table illustrating etching speed of Mo, Mo—Nb, Al, andAl—Nd;

FIGS. 40(a) and 40(b) are scanning electron microscope (SEM) picturesshowing etched profiles of thin films of Mo/Al/Mo.

FIGS. 41(a) and 41(b) are pictures showing etched profiles of thin filmsof Mo—Nb/Al/Mo; <Brief descriptions of the reference numerals> 110: aninsulating layer 121: a gate line 124: a gate electrode 131: a storageelectrode line 140: a gate insulating layer 150: an intrinsic amorphoussilicon layer 160: an extrinsic amorphous silicon layer 171: a data line173: a source electrode 175: a drain electrode 177: a storage conductor180: a passivation layer 182, 185, 187, 189: contact holes 901: a pixelelectrode 906, 908: contact assistants

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be describedmore fully hereinafter with reference to the accompanying drawings, inwhich preferred embodiments of the invention are shown. The presentinvention may, however, be practiced in different forms and should notbe construed as being limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the inventionto those skilled in the art.

In the drawings, the thickness of layers, films, and regions areexaggerated for clarity. Like numerals refer to like elementsthroughout. It will be understood that when an element such as a layer,film, region, or substrate is referred to as being “on” another element,it can be directly on the other element or intervening elements may alsobe present.

Now, TFT array panels and manufacturing methods thereof according toembodiments of this invention will be described in detail with referenceto the accompanying drawings so that a person of ordinary skill in therelevant art may easily carry them out.

Embodiment 1

At first, a TFT array panel for an LCD according to a first embodimentof the present invention will be described in detail with reference toFIGS. 1 and 2.

FIG. 1 is a layout view of a TFT array panel for an LCD according to anembodiment of the present invention and FIG. 2 is a sectional view ofthe TFT array panel shown in FIG. 1 taken along the line II-II.

A plurality of gate lines 121 for transmitting gate signals are formedon an insulating substrate 110. The gate lines 121 are mainly formed inthe horizontal direction and partial portions thereof become a pluralityof gate electrodes 124. Also, different partial portions thereof thatextend in a lower direction become a plurality of expansions 127.

The gate line 121 has lower layers 124 p and 127 p and upper layers 124q and 127 q. The lower layers 124 p and 127 p are made of Al or analuminum alloy such as aluminum-neodymium (Al—Nd). The upper layers 124q and 127 q are made of a molybdenum alloy (Mo-alloy), which is composedof molybdenum (Mo) and at least one of niobium (Nb), vanadium (V), andtitanium (Ti).

The upper layers 124 q and 127 q of Mo-alloy are formed on the lowerlayers 124 p and 127 p of Al or Al-alloy to prevent hillock growth thatmay arise in the lower layers 124 p and 127 p during a high temperatureprocess. The upper layers 124 q and 127 q of Mo-alloy may include 0.1 to10 at % (atomic percentage) of the additives Nb, V, and Ti. It is morepreferable that the upper layers 124 q and 127 q include 3 to 8 at % ofthe additives. When the content of the additives is increased,adhesiveness to other layers and the chemical resistance of the upperlayers 124 q and 127 q are improved, but resistivity of the upper layers124 q and 127 q increases. Accordingly, the content of the additives hasa preferable range.

FIG. 38 is a graph illustrating the variation of resistivity accordingto the included amount of Nb. According to FIG. 38, the resistivity ofthe Mo-alloy slowly increases along with an increase of the amount ofNb. Accordingly, when the resistivity, adhesiveness, and chemicalresistance are considered, the preferable content range of the additivesis determined as the above-described range.

A Mo-alloy, containing a predetermined amount of Nb, V, or Ti that makesan isomorphous solid solution with Mo, has better chemical resistance(slow etch speed) and less difference of chemical resistance with thelower layer of Al or Al-alloy than Mo itself. As the difference ofchemical resistance between the upper layers 124 q and 127 q and thelower layers 124 p and 124 p is reduced, undercut, overhang, and mousebites, which may arise in an etching process, are prevented.

FIG. 39 is a table illustrating etch speed of Mo, Mo—Nb, Al, and Al—Ndby a same etchant. According to FIG. 39, in a same etch condition, apure Mo layer is etched by about 170 Å/s and a Mo—Nb layer is etched byabout 44 Å/s. In other words the etch speed of the Mo—Nb layer is about¼ of that of the Mo layer.

As a result, the difference of etch speed between the Mo—Nb layer and anAl—Nd layer or Al layer, which are respectively etched by about 77 Å/sand 60 Å/s, is much less than that between the Mo layer and the Al—Ndlayer or Al layer. Accordingly, problems such as undercut, overhang, andmouse bite, which arise due to the difference of etching speed, areprominently reduced.

These results can be verified by FIGS. 40 and 41.

FIGS. 40(a) and 40(b) are scanning electron microscope (SEM) picturesshowing etched profiles of thin films of Mo/Al/Mo. FIG. 40(a) is a SEMpicture showing an etched profile of Mo/Al/Mo films etched by a commonetchant containing 67% of phosphoric acid, 6% of nitric acid, 10% ofacetic acid, and 17% of deionized water. FIG. 40(b) is a SEM pictureshowing an etched profile of Mo/Al/Mo films etched by a common etchantcontaining 67% of phosphoric acid, 13% of nitric acid, 15% of aceticacid, and 5% of deionized water.

FIGS. 41(a) and 41(b) are pictures showing etched profiles of thin filmsof Mo—Nb/Al/Mo. FIG. 41(a) is a SEM picture showing an etched profile ofMo—Nb/Al/Mo films etched by a common etchant containing 67% ofphosphoric acid, 13% of nitric acid, 15% of acetic acid, and 5% ofdeionized water. FIG. 41(b) is a SEM picture showing an etched profileof Mo—Nb/Al/Mo films etched by a common etchant containing 67% ofphosphoric acid, 6% of nitric acid, 10% of acetic acid, and 17% ofdeionized water.

When FIGS. 40(a) and 40(b) are compared to FIGS. 41(a) and 41(b),undercut, which is shown in FIGS. 40(a) and 40(b), is not shown in FIGS.41(a) and 41(b). This result is caused by the decreased etch speeddifference between the Mo—Nb layer and the Al—Nd layer, compared to thatof the Mo layer and the Al—Nd layer.

Returning again to FIG. 1 and FIG. 2, the lateral sides of the upperlayers 124 q and 127 q and lower layers 124 p and 127 q are inclinedrelative to a surface of the substrate 110, and the inclination anglethereof ranges from about 30-80 degrees.

A gate insulating layer 140 preferably made of silicon nitride (SiNx) isformed on the gate lines 121.

A plurality of semiconductor stripes 151 (or strips), preferably made ofhydrogenated amorphous silicon (abbreviated to “a-Si”), are formed onthe gate insulating layer 140. Each semiconductor stripe 151 extendssubstantially in the longitudinal direction and is curved periodically.Each semiconductor stripe 151 has a plurality of projections 154branching out toward the gate electrodes 124. The width of eachsemiconductor stripe 151 becomes large near the gate lines 121 such thatthe semiconductor stripe 151 covers large areas of the gate lines 121.

A plurality of ohmic contact stripes 161 and islands 165, preferablymade of silicide or n+ hydrogenated a-Si heavily doped with n typeimpurity, are formed on the semiconductor stripes 151. Each ohmiccontact stripe 161 has a plurality of projections 163, and theprojections 163 and the ohmic contact islands 165 are located in pairson the projections 154 of the semiconductor stripes 151.

The edge surfaces of the semiconductor stripes 151 and the ohmiccontacts 161 and 165 are tapered, and the inclination angles of the edgesurfaces of the semiconductor stripes 151 and the ohmic contacts 161 and165 are preferably in a range from about 30-80 degrees.

A plurality of data lines 171, a plurality of drain electrodes 175, anda plurality of storage capacitor conductors 177 are formed on the ohmiccontacts 161 and 165 and the gate insulating layer 140.

The data lines 171, for transmitting data voltages, extend in asubstantially longitudinal direction and intersect the gate lines 121 todefine pixel areas arranged in a matrix. A plurality of branches of eachdata line 171, projecting toward the drain electrodes 175, form aplurality of source electrodes 173. Each pair of the source electrodes173 and the drain electrodes 175 are separated from each other at thegate electrodes 124, and oppose each other.

The data line 171, the drain electrode 175, and the storage capacitorconductor 177 have first layers 171 p, 175 p, and 177 p, second layers171 q, 175 q, and 177 q, and third layers 171 r, 175 r, and 177 r. Thefirst layers 171 p, 175 p, and 177 p and the third layers 171 r, 175 r,and 177 r are respectively disposed at lower and upper sides of thesecond layers 171 q, 175 q, and 177 q. The first layers 171 p, 175 p,and 177 p and the third layers 171 r, 175 r, and 177 r are made of amolybdenum alloy (Mo-alloy), which is composed of molybdenum (Mo) and atleast one of niobium (Nb), vanadium (V), and titanium (Ti). Here, thefirst layers 171 p, 175 p, and 177 p and the third layers 171 r, 175 r,and 177 r of Mo-alloy may include 0.1 to 1 Oat % of the additives Nb, V,and Ti. It is more preferable that the first layers 171 p, 175 p, and177 p and the third layers 171 r, 175 r, and 177 r include 3 to 8 at %of the additives. When the content of the additives is increased,adhesiveness to other layers and the chemical resistance of the firstlayers 171 p, 175 p, and 177 p and the third layers 171 r, 175 r, and177 r are improved but resistivity of the first layers 171 p, 175 p, and177 p and the third layers 171 r, 175 r, and 177 r increases.Accordingly, the content of the additives has the above-describedpreferable range.

A Mo-alloy, containing a predetermined amount of Nb, V, or Ti which makean isomorphous solid solution with Mo, has better chemical resistance(slow etch speed) and less difference of chemical resistance with thelower layer of Al or Al-alloy than Mo itself. As the difference ofchemical resistance between the first and the third layers 171 p, 175 p,and 177 p and 171 r, 175 r, and 177 r and the second layers 171 q, 175q, and 177 q is reduced, undercut, overhang, and mouse bite, which mayarise in an etching process, are prevented.

FIG. 39 is a table illustrating etch speed of Mo, Mo—Nb, Al, and Al—Ndby a same etchant. According to FIG. 39, in a same etch condition, apure Mo layer is etched by about 170 Å/s and a Mo—Nb layer is etched byabout 44 Å/s. In other words the etch speed of the Mo—Nb layer is about¼ of that of the Mo layer.

As a result, the difference of etch speed between the Mo—Nb layer and anAl—Nd layer or an Al layer, which are respectively etched by about 77Å/s and 60 Å/s, is much less than that between the Mo layer and theAl—Nd layer or an Al layer. Accordingly, problems such as undercut,overhang, and mouse bite, which arise due to the difference of etchspeed, are prominently reduced.

These results can be verified by FIGS. 40 and 41.

FIGS. 40(a) and 40(b) are SEM pictures showing etched profiles of thinfilms of Mo/Al/Mo. FIG. 40(a) is a SEM picture showing an etched profileof Mo/Al/Mo films etched by a common etchant containing 67% ofphosphoric acid, 6% of nitric acid, 10% of acetic acid, and 17% ofdeionized water. FIG. 40(b) is a SEM picture showing an etched profileof Mo/Al/Mo films etched by a common etchant containing 67% ofphosphoric acid, 13% of nitric acid, 15% of acetic acid, and 5% ofdeionized water.

FIGS. 41(a) and 41(b) are pictures showing etched profiles of thin filmsof Mo—Nb/Al/Mo. FIG. 41(a) is a SEM picture showing an etched profile ofMo—Nb/Al/Mo films etched by a common etchant containing 67% ofphosphoric acid, 13% of nitric acid, 15% of acetic acid, and 5% ofdeionized water. FIG. 41(b) is a SEM picture showing an etched profileof Mo—Nb/Al/Mo films etched by a common etchant containing 67% ofphosphoric acid, 6% of nitric acid, 10% of acetic acid, and 17% ofdeionized water.

When FIGS. 40(a) and 40(b) are compared to FIGS. 41(a) and 41(b),undercut, which is shown in FIGS. 40(a) and 40(b), is not shown in FIGS.41(a) and 41(b). This result is caused by the decreased etch speeddifference between the Mo—Nb layer and the Al—Nd layer, compared to thatof the Mo layer and the Al—Nd layer.

Since the Al or Al-alloy layer, having low resistivity, is disposedbetween the two Mo-alloy layers, the data line 171 has a low resistivityand the Al or Al-alloy layer is prevented from contacting with thesemiconductor and pixel electrodes that may cause poor contact.Accordingly, degradation of TFTs caused by poor contacts is efficientlyprevented.

A gate electrode 124, a source electrode 173, and a drain electrode 175,along with a projection 154 of a semiconductor stripe 151, forms a TFTcell having a channel formed in the projection 154 disposed between thesource electrode 173 and the drain electrode 175. The storage capacitorconductor 177 is overlapped with the expansion 127 of the gate line 121.

The data lines 171, the drain electrodes 175, and the storage capacitorconductor 177 have tapered edge surfaces, and the inclination angles ofthe edge surfaces are in a range from about 30-80 degrees.

The ohmic contacts 161 and 165 are only interposed between thesemiconductor stripe 151 and the data line 171 and between the drainelectrode 175 and the projection 154 of the semiconductor stripe 151 inorder to reduce contact resistance therebetween. The semiconductorstripe 151 is partially exposed at the place between the sourceelectrode 173 and the drain electrode 175 and at the other places notcovered with the data line 171 and the drain electrode 175. Most of thesemiconductor stripe 151 is narrower than the data line 171, but thewidth of the semiconductor stripe 151 broadens near a place where thesemiconductor stripe 151 and the gate line 121 meet each other in orderto prevent disconnection of the data line 171, as mentioned in theabove.

On the data line 171, the drain electrode 175, the storage capacitorconductor 177, and the exposed region of the semiconductor stripe 151, apassivation layer 180 is provided, which is made of an organic materialhaving substantial planarization properties and photosensibility or aninsulating material with a low dielectric constant such as a-Si:C:O, aSi:O:F, etc. This passivation layer 180 is formed by a plasma enhancedchemical vapor deposition (PECVD) process. To prevent the organicmaterial of the passivation layer 180 from making contact with thesemiconductor strips 151 exposed between the data line 171 and the drainelectrode 175, the passivation layer 180 can be structured in such a waythat an insulating layer made of SiNx or SiO₂ is additionally formedunder the organic material layer.

In the passivation layer 180, a plurality of contact holes 185, 187, and182 are formed to expose the drain electrode 175, the storage capacitorconductor 177, and an end portion of the data line 171, respectively.

A plurality of pixel electrodes 190 and a plurality of contactassistants (or guides) 82, which are made of indium zinc oxide (IZO) orindium tin oxide (ITO), are formed on the passivation layer 180.

Since the pixel electrode 190 is physically and electrically connectedwith the drain electrode 175 and the storage capacitor conductor 177through the contact holes 185 and 187, respectively, the pixel electrode190 receives the data voltage from the drain electrodes 175 andtransmits it to the storage capacitor conductor 177.

The pixel electrode 190 to which the data voltage is applied, generatesan electric field with a common electrode (not shown) of the oppositepanel (not shown) to which a common voltage is applied, so that theliquid crystal molecules in the liquid crystal layer are rearranged.

Also, as mentioned in the above, the pixel electrode 190 and the commonelectrode form a capacitor to store and preserve the received voltageafter the TFT is turned off. This capacitor will be referred to as a“liquid crystal capacitor.” To enhance the voltage storage ability,another capacitor is provided, which is connected with the liquidcrystal capacitor in parallel and will be referred to as a “storagecapacitor.” The storage capacitor is formed at an overlapping portion ofthe pixel electrode 190 and the adjacent gate line 121, which will bereferred to as a “previous gate line.” The expansion 127 of the gateline 121 is provided to ensure the largest possible overlap dimensionand thus to increase storage capacity of the storage capacitor. Thestorage capacitor conductor 177 is connected to the pixel electrode 190and is overlapped with the expansion 127, and is provided at the bottomof the passivation layer 180 so that the pixel electrode 190 is close tothe previous gate line 121.

The pixel electrode 190 is overlapped with the adjacent gate line 121and the adjacent data line 171 to enhance the aperture ratio, but it isnot required.

The contact assistant 82 supplements adhesion between the end portion ofthe data line 171 and the exterior devices, such as the drivingintegrated circuit, and protects them. Applying the contact assistant 82is optional since it is not an essential element.

A method of manufacturing a TFT array panel will be now described indetail with reference to FIGS. 3A to 6B as well as FIGS. 1 and 2.

FIGS. 3A, 4A, 5A, and 6A are layout views sequentially illustrating theintermediate steps of a method of manufacturing a TFT array panel for anLCD according to the embodiment of FIGS. 1 and 2; FIG. 3B is a sectionalview of the TFT array panel shown in FIG. 3A taken along the lineIIIb-IIIb′. FIG. 4B is a sectional view of the TFT array panel shown inFIG. 4A taken along the line IVb-IVb′ in the step following the stepshown in FIG. 3B. FIG. 5B is a sectional view of the TFT array panelshown in FIG. 5A taken along the line Vb-Vb′ in the step following thestep shown in FIG. 4B. FIG. 6B is a sectional view of the TFT arraypanel shown in FIG. 6A taken along the line VIb-VIb′ in the stepfollowing the step shown in FIG. 5B.

At first, as shown in FIG. 3B, a metal layer is formed on an insulatingsubstrate 110.

The metal layer is deposited by a Co-sputtering. Two targets areinstalled in a same sputtering chamber for the Co-sputtering. One targetis made of Al or Al—Nd. The other target is made of a molybdenum alloy(Mo-alloy), which is composed of molybdenum (Mo) and at least one ofniobium (Nb), vanadium (V), and titanium (Ti). Here, the Al—Nd targetpreferably contains 2 at % of Nd. The Mo-alloy target may include 0.1 to1 Oat % of the additives Nb, V, and Ti, and more preferably includes 3to 8 at % of the additives. When the content of the additives isincreased, adhesiveness to other layers and chemical resistance isimproved but resistivity increases. Accordingly, the content of theadditives has the above preferable range.

The Co-sputtering process is performed as follows.

At first, power is applied to the Al (or Al—Nd) target while no power isapplied to the Mo-alloy target to deposit a lower layer of Al (orAl—Nd). The thickness of the lower layer is preferably 2,500 Å.

Next, power is switched to be applied to the Mo-alloy target and not tobe applied to the Al (or Al—Nd) target to deposit an upper layer.

The upper and lower layers are simultaneously etched to form a pluralityof gate lines 121 having a plurality of gate electrodes 124 andexpansions 127. Here, the upper and lower layers are preferably etchedby an etchant containing phosphoric acid, nitric acid, acetic acid, anddeionized water. More precisely, the etchant may include 63% to 70% ofphosphoric acid, 4% to 8% of nitric acid, 8% to 11% of acetic acid, anddeionized water for the residual quantity. The etchant may include moreacetic acid by about 4% to 8%.

Referring to FIGS. 4A and 4B, after sequential deposition of a gateinsulating layer 140, an intrinsic a-Si layer, and an extrinsic a-Silayer, the extrinsic a-Si layer and the intrinsic a-Si layer arephoto-etched to form a plurality of extrinsic semiconductor stripes 161and a plurality of intrinsic semiconductor stripes 151 respectivelyhaving projections 164 and 154. The gate insulating layer 140 ispreferably made of silicon nitride with a thickness of about 2,000 Å toabout 5,000 Å, and the deposition temperature is preferably in a rangebetween about 250° C. and about 500° C.

Next, a first layer of Mo-alloy, a second layer of Al (or Al-alloy), anda third layer of Mo-alloy are sequentially deposited on the extrinsicsemiconductor stripes 161 by a Co-sputtering. The first and third layersare made of a molybdenum alloy (Mo-alloy), which is composed ofmolybdenum (Mo) and at least one of niobium (Nb), vanadium (V), andtitanium (Ti). Here, one of the first layer and third layer may beformed with another material. The thickness of the three layers ispreferably about 3,000 Å. The sputtering temperature is preferably about150° C.

Next, as shown in FIGS. 5A and 5B, the three layers are simultaneouslyetched to form data lines 171, drain electrodes 175, and storageconductors 177 by an etchant. Here, the three layers are preferablyetched by an etchant containing phosphoric acid, nitric acid, aceticacid, and deionized water. Precisely, the etchant may include 63% to 70%of phosphoric acid, 4% to 8% of nitric acid, 8% to 11% of acetic acid,and deionized water for the residual quantity. The etchant may includemore acetic acid by about 4% to 8%.

Next, portions of the extrinsic semiconductor stripes 161, which are notcovered with the data lines 171 and the drain electrodes 175, areremoved by etching to complete a plurality of ohmic contacts 163 and 165and to expose portions of the intrinsic semiconductor stripes 151.Oxygen plasma treatment may follow thereafter in order to stabilize theexposed surfaces of the semiconductor stripes 151.

Referring to FIGS. 6A and 6B, a passivation layer 180 is deposited anddry etched along with the gate insulating layer 140 to form a pluralityof contact holes 185, 187, and 182. The gate insulating layer 140 andthe passivation layer 180 are preferably etched under an etch conditionhaving substantially the same etch ratio for both the gate insulatinglayer 140 and the passivation layer 180.

Finally, as shown in FIGS. 1 and 2, a plurality of pixel electrodes 190and a plurality of contact assistants 82 are formed by sputtering andphoto-etching an IZO layer or an ITO layer.

The present embodiment discloses gate lines 121 and data lines 171 bothhaving a Mo containing layer and an Al containing layer. However, it ispossible that only one of the gate lines 121 and data lines 171 havemulti-layers.

Embodiment 2

The data lines and the semiconductors are formed by different photoetching processes using different photo masks than in the firstembodiment. However, the data lines and the semiconductors may besimultaneously formed by a photo etching process using a same photo maskto reduce production costs. Such an embodiment will be described indetail with reference to the drawings.

FIG. 7 is a layout view of a TFT array panel for an LCD according toanother embodiment of the present invention. FIG. 8 is a sectional viewof the TFT array panel shown in FIG. 7 taken along the line VIII-VIII′.

Referring to FIGS. 7 and 8, a plurality of gate lines 121, including aplurality of gate electrodes 124 and a plurality of storage electrodelines 131 which are electrically separated from the gate lines 121, areformed on a substrate 110.

The gate lines 121 and the storage electrode lines 131 have lower layers121 p and 131 p and upper layers 121 q and 131 q. The lower layers 121 pand 131 p are made of Al or an aluminum alloy such as aluminum-neodymium(Al—Nd). The upper layers 121 q and 131 q are made of a molybdenum alloy(Mo-alloy), which is composed of molybdenum (Mo) and at least one ofniobium (Nb), vanadium (V), and titanium (Ti). The upper layer 124 q ofthe Mo-alloy may include 0.1 to 10 at % of the additives Nb, V, and Ti.It is more preferable that the upper layer 124 q includes 3 to 8 at % ofthe additives.

In addition, the lateral sides of the lower films 121 p and 131 p andthe upper films 121 q and 131 q are inclined relative to a surface ofthe substrate 110, and the inclination angle thereof ranges from about30-80 degrees.

A gate insulating layer 140 preferably made of silicon nitride (SiNx) isformed on the gate lines 121 and the storage electrode lines 131.

A plurality of semiconductor stripes 151 preferably made of hydrogenatedamorphous silicon (abbreviated to “a-Si”) are formed on the gateinsulating layer 140. Each semiconductor stripe 151 extendssubstantially in the longitudinal direction and has a plurality ofprojections 154 branching out toward the gate electrodes 124. Theprojections 154 have portions overlapping the storage electrode line131.

A plurality of ohmic contact stripes 161 and islands 165 preferably madeof silicide or n+ hydrogenated a-Si heavily doped with n type impurityare formed on the semiconductor stripes 151. Each ohmic contact stripe161 has a plurality of projections 163, and the projections 163 and theohmic contact islands 165 are located in pairs on the projections 154 ofthe semiconductor stripes 151.

The lateral sides of the semiconductors 151 and the ohmic contacts 161and 165 are inclined relative to a surface of the substrate 110, and theinclination angles thereof preferably range between about 30-80 degrees.

A plurality of data lines 171 and a plurality of drain electrodes 175are formed on the ohmic contacts 161 and 165 and the gate insulatinglayer 140.

The data lines 171 for transmitting data voltages extend substantiallyin the longitudinal direction and intersect the gate lines 121 to definepixel areas arranged in a matrix. A plurality of branches of each dataline 171 that project toward the drain electrodes 175 form a pluralityof source electrodes 173. Each pair of the source electrodes 173 and thedrain electrodes 175 are separated from each other by a gate electrode124 and oppose each other.

The data line 171 and the drain electrode 175 have first layers 171 pand 175 p, second layers 171 q and 175 q, and third layers 171 r and 175r. The first layers 171 p and 175 p and third layers 171 r and 175 r arerespectively disposed at lower and upper sides of the second layers 171q and 175 q. The first layers 171 p and 175 p and the third layers 171 rand 175 r are made of a molybdenum alloy (Mo-alloy), which is composedof molybdenum (Mo) and at least one of niobium (Nb), vanadium (V), andtitanium (Ti). Here, the first layers 171 p and 175 p and the thirdlayers 171 r and 175 r of Mo-alloy may include 0.1 to 10 at % of theadditives Nb, V, and Ti. It is more preferable that the first layers 171p and 175 p and the third layers 171 r and 175 r include 3 to 8 at % ofthe additives.

The ohmic contacts 161 and 165 are interposed only between theunderlying semiconductors 151 and the overlying data lines 171 and drainelectrodes 175, and reduce the contact resistance therebetween. Thesemiconductor stripes 151 include a plurality of exposed portions, whichare not covered with the data lines 171 and the drain electrodes 175,such as portions located between the source electrodes 173 and the drainelectrodes 175.

A passivation layer 180 is formed on the data lines 171, the drainelectrodes 175, and exposed portions of the semiconductor stripes 151,which are not covered with the data lines 171 and the drain electrodes175. The passivation layer 180 is preferably made of a photosensitiveorganic material having good planarity, a dielectric insulating materialhaving a low dielectric constant under 4.0, such as a-Si:C:O anda-Si:O:F formed by plasma enhanced chemical vapor deposition (PECVD), oran inorganic material such as silicon nitride and silicon oxide.

The passivation layer 180 has a plurality of contact holes 182 and 185.

A plurality of pixel electrodes 190 and a plurality of contactassistants 82 are formed on the passivation layer 180.

The pixel electrodes 190 are physically and electrically connected tothe drain electrodes 175 through the contact holes 185 such that thepixel electrodes 190 receive the data voltages from the drain electrodes175. The pixel electrodes 190, supplied with the data voltages, generateelectric fields in cooperation with a common electrode (not shown) onanother panel (not shown), which reorient liquid crystal molecules in aliquid crystal layer (not shown) disposed therebetween.

A pixel electrode 190 and a common electrode form a liquid crystalcapacitor, which stores applied voltages after turning-off the TFT. Anadditional capacitor called a “storage capacitor” is connected inparallel to the liquid crystal capacitor. The storage capacitors areimplemented by overlapping the pixel electrodes 190 with the storagelines 131. The storage electrode lines 131 are supplied with apredetermined voltage such as the common voltage. The storage electrodelines 131 may be omitted if the storage capacitance generated by theoverlapping of the gate lines 121 and the pixel electrodes 190 issufficient. The storage electrode lines 131 may be formed along aboundary of the pixels to enhance an aperture ratio.

A method of manufacturing the TFT array panel illustrated in FIGS. 7 and8 will be now described in detail with reference to FIGS. 9A to 13C aswell as FIGS. 7 and 8.

Two layers, a lower layer and an upper layer, are sputtered in sequenceonto an insulating substrate 110 such as transparent glass. The lowerlayer is preferably made of an aluminum alloy such as Al—Nd. The upperlayer is preferably made of a molybdenum alloy (Mo-alloy), which iscomposed of molybdenum (Mo) and at least one of niobium (Nb), vanadium(V), and titanium (Ti).

Referring to FIGS. 9A and 9B, the upper layer and the lower layer arepatterned in sequence by photo-etching with a photoresist pattern toform a plurality of gate lines 121, including a plurality of gateelectrodes 124, and a plurality of storage electrode lines 131.

Referring to FIG. 10, a gate insulating layer 140 made of SiNx, anintrinsic semiconductor layer 150, and an extrinsic semiconductor layer160 are sequentially deposited. The intrinsic semiconductor layer 150 ispreferably made of hydrogenated amorphous silicon (abbreviated to“a-Si”) and the extrinsic semiconductor layer 160 is preferably made ofsilicide or n+ hydrogenated a-Si heavily doped with n type impurity.

Next, a first layer 170 p of Mo-alloy, a second layer 170 q of Al (or anAl-alloy), and a third layer 170 r of Mo-alloy are sequentiallydeposited on the extrinsic semiconductor layer 160. The first and thirdlayers 170 p and 170 r are made of a molybdenum alloy (Mo-alloy), whichis composed of molybdenum (Mo) and at least one of niobium (Nb),vanadium (V), and titanium (Ti). Here, one of the first layer 170 p andthird layer 170 q may be formed of pure Mo or another material.

A photoresist film is coated on the third layer 170 r. The photoresistfilm is exposed to light through an exposure mask (not shown), anddeveloped such that the developed photoresist has a position dependentthickness as shown in FIG. 10. The developed photoresist includes aplurality of first to third portions 54 and 52. The first portions 54are located on channel areas B and the second portions 52 are located onthe data line areas A. No reference numeral is assigned to the thirdportions located on the remaining areas C since they have essentiallyzero thickness. Here, the thickness ratio of the first portions 54 tothe second portions 52 is adjusted depending upon the process conditionsin the subsequent process steps. It is preferable that the thickness ofthe first portions 54 is equal to or less than half of the thickness ofthe second portions 52.

The position-dependent thickness of the photoresist is obtained byseveral techniques, for example, by providing translucent areas on theexposure mask as well as transparent areas and light blocking opaqueareas. The translucent areas may have a slit pattern, a lattice pattern,and thin film(s) with intermediate transmittance or intermediatethickness. When using a slit pattern, it is preferable that the width ofthe slits or the distance between the slits is smaller than theresolution of a light exposure used for the photolithography. Anotherexample is to use reflowable photoresist. In detail, once a photoresistpattern made of a reflowable material is formed by using a normalexposure mask only with transparent areas and opaque areas, it issubject to a reflow process to flow onto areas without the photoresist,thereby forming thin portions.

Next, the photoresist film 52 and 54 and the underlying layers areetched such that the data lines 171, drain electrodes 175, and theunderlying layers are left on the data areas A, only the intrinsicsemiconductor layer is left on the channel areas B, and the gateinsulating layer 140 is exposed on the remaining areas C.

A method to form such a structure will be now described.

Referring to FIG. 11, the exposed portions of the first to third layers170 p, 170 q, and 170 r on the other areas C are removed to expose theunderlying portions of the extrinsic semiconductor layer 160.

Next, referring to FIG. 11, the exposed portions of the extrinsicsemiconductor layer 160 and the underlying portions of the intrinsicsemiconductor layer 150 on the areas C as well as the photoresistpattern 54 and 52 are removed by dry etching to exposeS(source)/D(drain) metals 174 of the areas B.

The photoresist pattern 54 of the channel areas B may be simultaneouslyremoved by an etching for removing the extrinsic semiconductor 160 andthe intrinsic semiconductor 150 or by a separate etching. Residualphotoresist of the photoresist pattern 54 in the channel area B isremoved by ashing. In this step, the semiconductor strips 151 arecompletely formed.

Next, as shown in FIGS. 12A and 12B, portions of the S/D metals 174 andthe underlying portions of the extrinsic semiconductor layer 164 on thechannel areas B are etched to be removed. At this time, the exposedportions of the semiconductor 154 may be etched to have a reducedthickness and the second portion 52 of the photoresist pattern may alsobe partially removed.

Accordingly, the source electrodes 173 and the drain electrodes 175 areseparated from each other, and, simultaneously, the data lines and theohmic contacts 163 and 165 thereunder are completed.

Finally, the residual second portions 52 of the photoresist pattern lefton the data areas A are removed.

In the above description, the first to third layers 170 p, 170 q, and170 r are preferably etched by an etchant containing phosphoric acid,nitric acid, acetic acid, and deionized water. Precisely, the etchantmay include 63% to 70% of phosphoric acid, 4% to 8% of nitric acid, 8%to 11% of acetic acid, and deionized water for the residual quantity.The etchant may include more acetic acid by about 4% to 8%.

Thereafter, as shown in FIGS. 13A and 13B, a passivation layer 180 isformed to cover the data lines 171, the drain electrodes 175, and theexposed portions of the semiconductor stripes 151, which are not coveredwith the data lines 171 and the drain electrodes 175. The passivationlayer 180 is preferably made of a photosensitive organic material havinggood planarity, a dielectric insulating material having a low dielectricconstant under 4.0, such as a-Si:C:O and a-Si:O:F, formed by plasmaenhanced chemical vapor deposition (PECVD), or an inorganic material,such as silicon nitride and silicon oxide.

Next, the passivation layer 180 is photo-etched to form a plurality ofcontact holes 185 and 182. When the passivation layer 180 is made of aphotosensitive material, the contact holes 185 and 182 may be formedonly by photolithography.

Finally, as shown in FIGS. 7 and 8, a plurality of pixel electrodes 190and a plurality of contact assistants 82 are formed by sputtering andphoto-etching an IZO layer or an ITO layer. The pixel electrodes 190 andthe contact assistants 82 are respectively connected to the drainelectrodes 175 and an end of the data lines 171 through the contactholes 185 and 182.

The present embodiment illustrates gate lines 121 and data lines 171both having a Mo containing layer and an Al containing layer. However,it is possible that only one of the gate lines 121 and data lines 171have multi-layers.

Embodiment 3

The present embodiment illustrates a thin film transistor (TFT) arraypanel having color filters.

FIG. 14A is a layout view of a TFT array panel for an LCD according toanother embodiment of the present invention. FIG. 14B is a sectionalview of the TFT array panel shown in FIG. 14A taken along the lineXIVB-XIVB′.

A plurality of gate lines 121 for transmitting gate signals are formedon an insulating substrate 110. The gate lines 121 are mainly formed inthe horizontal direction and the partial portions thereof become aplurality of gate electrodes 124. Also, different partial portionsthereof, which extend in a lower direction, become a plurality ofexpansions 127.

The gate line 121 has lower layers 124 p and 127 p and upper layers 124q and 127 q. The lower layers 124 p and 127 p are made of aluminum (Al)or an aluminum alloy such as aluminum-neodymium (Al—Nd). The upperlayers 124 q and 127 q are made of a molybdenum alloy (Mo-alloy: Mo—Nb,Mo—V, Mo—Ti), which is composed of molybdenum (Mo) and at least one ofniobium (Nb), vanadium (V), and titanium (Ti).

The upper layers 124 q and 127 q of Mo-alloy are formed on the lowerlayers 124 p and 127 p of Al or Al-alloy to prevent hillock growth,undercut, overhang, and mouse bites, which may arise in the etchingprocess.

The upper layers 124 q and 127 q of Mo-alloy may include 0.1 to 1 Oat %of the additives Nb, V, and Ti. It is more preferable that the upperlayers 124 q and 127 q include 3 to 8 at % of the additives. When thecontent of the additives is increased, adhesiveness to other layers andchemical resistance of the upper layers 124 q and 127 q are improved,but resistivity of the upper layer 124 q and 127 q increases.Accordingly, the content of the additives has the above-describedpreferable range.

FIG. 38 is a graph illustrating variation of resistivity according tothe included amount of Nb. According to FIG. 38, the resistivity of theMo-alloy is almost linearly proportioned to the amount of Nb.Accordingly, when the resistivity, adhesiveness, and chemical resistanceare considered, the preferable content range of the additives isdetermined as the above-described range.

The lateral sides of the upper layers 124 q and 127 q and lower layers124 p and 127 q are inclined relative to a surface of the substrate 110,and the inclination angle thereof ranges from about 30-80 degrees.

A gate insulating layer 140 preferably made of silicon nitride (SiNx) isformed on the gate lines 121.

A plurality of semiconductor stripes 151 preferably made of hydrogenatedamorphous silicon (abbreviated to “a-Si”) is formed on the gateinsulating layer 140. Each semiconductor stripe 151 extendssubstantially in the longitudinal direction and is curved periodically.Each semiconductor stripe 151 has a plurality of projections 154branched out toward the gate electrodes 124. The width of eachsemiconductor stripe 151 becomes large near the gate lines 121 such thatthe semiconductor stripe 151 covers large areas of the gate lines 121.

A plurality of ohmic contact stripes 161 and islands 165, preferablymade of silicide or n+ hydrogenated a-Si heavily doped with n typeimpurity, are formed on the semiconductor stripes 151. Each ohmiccontact stripe 161 has a plurality of projections 163, and theprojections 163 and the ohmic contact islands 165 are located in pairson the projections 154 of the semiconductor stripes 151.

The edge surfaces of the semiconductor stripes 151 and the ohmiccontacts 161 and 165 are tapered, and the inclination angles of the edgesurfaces of the semiconductor stripes 151 and the ohmic contacts 161 and165 are preferably in a range from about 30-80 degrees.

A plurality of data lines 171, a plurality of drain electrodes 175, anda plurality of storage capacitor conductors 177 are formed on the ohmiccontacts 161 and 165 and the gate insulating layer 140.

The data lines 171 for transmitting data voltages extend substantiallyin the longitudinal direction and intersect the gate lines 121 to definepixel areas arranged in a matrix. A plurality of branches of each dataline 171 that project toward the drain electrodes 175 form a pluralityof source electrodes 173. Each pair of the source electrodes 173 and thedrain electrodes 175 are separated from each other at on a gateelectrode 124 and are opposite to each other.

A gate electrode 124, a source electrode 173, and a drain electrode 175,along with a projection 154 of a semiconductor stripe 151, form a TFThaving a channel formed in the projection 154 disposed between thesource electrode 173 and the drain electrode 175. The storage capacitorconductor 177 is overlapped with the expansion 127 of the gate line 121.

The data lines 171, the drain electrode 175, and the storage capacitorconductor 177 may be made of a metal such as Cr, Ti, Ag, Mo, Ta, or anAl containing metal (Al, or Al-alloy). When the data lines 171, thedrain electrode 175, and the storage capacitor conductor 177 include anAl containing metal layer, the data lines 171, the drain electrode 175,and the storage capacitor conductor 177 further include another layermade of Cr, Ti, Ta, Mo, or their alloys which have good physical,chemical, and electrical contact characteristics with other materialssuch as indium tin oxide (ITO) and indium zinc oxide (IZO). However, thedata lines 171, the drain electrode 175, and the storage capacitorconductor 177 preferably have first layers 171 p, 175 p, and 177 p,second layers 171 q, 175 q, and 177 q, and third layers 171 r, 175 r,and 177 r. The first layers 171 p, 175 p, and 177 p and third layers 171r, 175 r, and 177 r are respectively disposed at lower and upper sidesof the second layers 171 q, 175 q, and 177 q. The first layers 171 p,175 p, and 177 p and the third layers 171 r, 175 r, and 177 r are madeof a molybdenum alloy (Mo-alloy), which is composed of molybdenum (Mo)and at least one of niobium (Nb), vanadium (V), and titanium (Ti). Here,the first layers 171 p, 175 p, and 177 p and the third layers 171 r, 175r, and 177 r of Mo-alloy may include 0.1 to 10 at % of the additives Nb,V, and Ti. It is more preferable that the first layers 171 p, 175 p, and177 p and the third layers 171 r, 175 r, and 177 r include 3 to 8 at %of the additives. When the content of the additives is increased,adhesiveness to other layers and chemical resistance of the first layers171 p, 175 p, and 177 p and the third layers 171 r, 175 r, and 177 r areimproved but resistivity of the first layers 171 p, 175 p, and 177 p andthe third layers 171 r, 175 r, and 177 r increases. Accordingly, thecontent of the additives has the above preferable range.

A Mo-alloy, containing a predetermined amount of Nb, V, or Ti which makean isomorphous solid solution with Mo, has better chemical resistance(slow etch speed) and less difference of chemical resistance with thelower layer of Al or Al alloy than Mo itself. As the difference ofchemical resistance between the first and the third layers 171 p, 175 p,and 177 p and 171 r, 175 r, and 177 r and the second layers 171 q, 175q, and 177 q is reduced, undercut, overhang, and mouse bites, which mayarise in an etching process, are prevented.

The data lines 171, the drain electrodes 175, and the storage capacitorconductor 177 have tapered edge surfaces, and the inclination angles ofthe edge surfaces are in a range from about 30-80 degrees.

The ohmic contacts 161 and 165 are only interposed between thesemiconductor stripe 151 and the data line 171 and between the drainelectrode 175 and the projection 154 of the semiconductor stripe 151 inorder to reduce contact resistance therebetween. The semiconductorstripe 151 is partially exposed at a place between the source electrode173 and the drain electrode 175 and at other places not covered with thedata line 171 and the drain electrode 175. Most of the semiconductorstripe 151 is narrower than the data line 171 but the width of thesemiconductor stripe 151 broadens near a place where the semiconductorstripe 151 and the gate line 121 meet each other in order to preventdisconnection of the data line 171, as mentioned in the above.

It is a distinguishing feature of the present embodiment that colorfilters 230R, 230G, and 230B are formed on the data line 171, the drainelectrode 175, and the storage capacitor conductor 177. The colorfilters 230R, 230G, and 230B are formed along pixel columns that arepartitioned by data lines 171. The red, green, and blue color filters230R, 230G, and 230B are illuminated or energized in turn.

The color filters 230R, 230G, and 230B are not formed on the endportions of the gate lines 121 and the data lines 171, which areconnected to external circuits. Two adjacent color filters 230R, 230G,and 230B overlap each other on the data lines 171. Accordingly, lightleakage that may arise around a pixel area is prevented by theoverlapped color filters 230R, 230G, and 230B. All of the red, green,and blue color filters 230R, 230G, and 230B may be disposed on the dataline 171 so as to overlap each other.

A first interlayer insulating layer 801 is formed under the colorfilters 230R, 230G, and 230B to prevent pigments of the color filters230R, 230G, and 230B from penetrating into the semiconductor protrusion154. A second interlayer insulating layer 802 is formed on the colorfilters 230R, 230G, and 230B to prevent pigments of the color filters230R, 230G, and 230B from penetrating into a liquid crystal layer (notillustrated).

The interlayer insulating layers 801 and 802 may be made of aninsulating material with a low dielectric constant such as a-Si:C:O anda-Si:O:F, or SiNx.

As described above, when the color filters 230R, 230G, and 230B areformed on the thin film transistor array panel and overlap each other onthe data line 171, the opposite panel may have only a common electrode.Accordingly, assembling of the TFT panel and opposite panel is easy andthe aperture ratio increases.

In the second interlayer insulating layer 802, a plurality of contactholes 185, 187, and 182 are formed to expose the drain electrode 175,the storage capacitor conductor 177, and an end portion of the data line171 respectively.

A plurality of pixel electrodes 190 and a plurality of contactassistants 82, which are made of IZO or ITO, are formed on thepassivation layer 180.

Since the pixel electrode 190 is physically and electrically connectedwith the drain electrode 175 and the storage capacitor conductor 177through the contact holes 185 and 187, respectively, the pixel electrode190 receives the data voltage from the drain electrodes 175 andtransmits it to the storage capacitor conductor 177.

The pixel electrode 190, to which the data voltage is applied, generatesan electric field with a common electrode (not shown) of the oppositepanel (not shown) to which common voltage is applied, so that the liquidcrystal molecules in the liquid crystal layer are rearranged.

The contact assistant 82 supplements adhesion between the end portion ofthe data line 171 and the exterior devices such as the drivingintegrated circuit and protects them. Applying the contact assistant 82is optional since it is not an essential element.

A method of manufacturing a TFT array panel will now be described indetail with reference to FIGS. 15A to 16B as well as FIGS. 14A and 14B.

Referring to FIGS. 15A and 15B, a plurality of gate lines 121 havinglower layers 124 p and 127 p of Al or Al-alloy and upper layers 124 qand 127 q of a molybdenum alloy (Mo-alloy), which is composed ofmolybdenum (Mo) and at least one of niobium (Nb), vanadium (V), andtitanium (Ti), are formed on an insulating substrate 110 of glass.

A gate insulating layer 140, a plurality of semiconductor stripes 151, aplurality of ohmic contact assistants 161 and 165, and a plurality ofdata lines 171 and drain electrodes 175 are sequentially formed on thegate lines 121.

Next, organic photo-resist materials respectively containing pigments ofred, green, and blue are coated and are patterned by a photo process toform a plurality of color filters 230R, 230G, and 230B in sequence.Here, a first interlayer insulating layer 801 made of an inorganicinsulating material such as SiNx or SiO₂ is formed on the data lines 171and drain electrodes 175 before forming the color filters 230R, 230G,and 230B. The first interlayer insulating layer 801 prevents pigments ofthe color filters 230R, 230G, and 230B from penetrating into thesemiconductor protrusion 154. At this time, openings 235 and 237exposing the drain electrode 175 and the storage capacitor conductor 177are simultaneously formed.

Referring to FIGS. 16A and 16B, a second interlayer insulating layer 802is formed by the coating of an organic insulating film having a lowdielectric constant and good planarity, or by the PECVD of a lowdielectric insulating material such as a-Si:C:O and a-Si:O:F having adielectric constant lower than about 4.0.

Thereafter, the first and second interlayer insulating layers 801 and802 are photo-etched to form a plurality of contact holes 182, 185, and187. Here, the contact holes 185 and 187 exposing the drain electrodes175 and the storage capacitor conductor 177 are formed in the openings235 and 237 of the color filters 230R, 230G, and 230B.

Finally, as shown in FIG. 14B, a plurality of pixel electrodes 190 and aplurality of contact assistants 82 are formed by sputtering andphoto-etching an IZO layer or an ITO layer. The pixel electrodes 190 areconnected to the drain electrodes 175 and the storage capacitorconductor 177 through the contact holes 185 and 187.

The present embodiment illustrates gate lines 121 and data lines 171both having a Mo containing layer and an Al containing layer. However,it is possible that only one of the gate lines 121 and data lines 171has multi-layers.

Embodiment 4

Now, a TFT panel for an active matrix organic light emitting display(AM-OLED) according to another embodiment of the present invention willbe described.

FIG. 17 is a layout view of a TFT array panel for an LCD according toanother embodiment of the present invention. FIGS. 18 and 19 aresectional views of the TFT array panel shown in FIG. 17 that are takenalong the line XVIII-XVIII′ and the line XIX-XIX′, respectively. FIGS.20 and 21 are sectional views of the TFT array panel shown in FIG. 17that are taken along the line XX-XX′ and the line XXI-XXI′,respectively.

A plurality of gate conductors that include a plurality of gate lines121, including a plurality of first gate electrodes 124 a and aplurality of second gate electrodes 124 b, are formed on an insulatingsubstrate 110 such as transparent glass.

The gate lines 121 transmitting gate signals extend substantially in atransverse direction and are separated from each other. The first gateelectrodes 124 a protrude upward. The gate lines 121 may extend to beconnected to a driving circuit (not shown) integrated on the substrate110, or it may have an end portion (not shown) having a large area forconnection with another layer or an external driving circuit mounted onthe substrate 110 or on another device such as a flexible printedcircuit film (not shown) that may be attached to the substrate 110.

Each of the second gate electrodes 124 b is separated from the gatelines 121 and includes a storage electrode 133 extending in asubstantially transverse direction between two adjacent gate lines 121.

The gate lines 121, the first and second gate electrodes 124 a and 124b, and the storage electrodes 133 have lower layers 124 ap and 124 bpand upper layers 124 aq and 124 bq. The lower layers 124 ap and 124 bpare made of aluminum (Al) or an aluminum alloy such asaluminum-neodymium (Al—Nd). The upper layers 124 aq and 124 bq are madeof a molybdenum alloy (Mo-alloy: Mo—Nb, Mo—V, Mo—Ti), which is composedof molybdenum (Mo) and at least one of niobium (Nb), vanadium (V), andtitanium (Ti).

The upper layers 124 aq and 124 bq of Mo-alloy may include 0.1 to 1 Oat% of the additives Nb, V, and Ti. It is more preferable that the upperlayers 124 aq and 124 bq include 3 to 8 at % of the additives. When thecontent of the additives is increased, adhesiveness to other layers andchemical resistance of the upper layers 124 aq and 124 bq is improved,but resistivity of the upper layers 124 aq and 124 bq increases.Accordingly, the content of the additives has the above preferablerange.

In addition, the lateral sides of the gate conductors 121 and 124 b areinclined relative to a surface of the substrate 110, and the inclinationangle thereof ranges from about 30-80 degrees.

A gate insulating layer 140, preferably made of silicon nitride (SiNx),is formed on the gate conductors 121 and 124 b.

A plurality of semiconductor stripes 151 and islands 154 b, preferablymade of hydrogenated amorphous silicon (abbreviated to “a-Si”) orpolysilicon, are formed on the gate insulating layer 140. Eachsemiconductor stripe 151 extends substantially in a longitudinaldirection and has a plurality of projections 154 a branching out towardthe first gate electrodes 124 a. Each semiconductor island 154 b crossesa second gate electrode 124 b and includes a portion 157 overlapping thestorage electrode 133 of the second gate electrode 124 b.

A plurality of ohmic contact stripes 161 and ohmic contact islands 163b, 165 a, and 165 b, which are preferably made of silicide or n+hydrogenated a-Si heavily doped with n type impurity such asphosphorous, are formed on the semiconductor stripes 151 and islands 154b. Each ohmic contact stripe 161 has a plurality of projections 163 a,and the projections 163 a and the ohmic contact islands 165 a arelocated in pairs on the projections 154 a of the semiconductor stripes151. The ohmic contact islands 163 b and 165 b are located in pairs onthe semiconductor islands 154 b.

The lateral sides of the semiconductor stripes 151 and islands 154 b andthe ohmic contacts 161, 163 b, 165 b, and 165 b are inclined relative toa surface of the substrate, and the inclination angles thereof arepreferably in a range between about 30-80 degrees.

A plurality of data conductors including a plurality of data lines 171,a plurality of voltage transmission lines 172, and a plurality of firstand second drain electrodes 175 a and 175 b are formed on the ohmiccontacts 161, 163 b, 165 b, and 165 b and the gate insulating layer 140.

The data lines 171 for transmitting data signals extend in asubstantially longitudinal direction and intersect the gate lines 121.Each data line 171 includes a plurality of first source electrodes 173 aand an end portion having a large area for contact with another layer oran external device. The data lines 171 may be directly connected to adata driving circuit for generating the gate signals, which may beintegrated onto the substrate 110.

The voltage transmission lines 172 for transmitting driving voltagesextend in a substantially longitudinal direction and intersect the gatelines 121. Each voltage transmission line 172 includes a plurality ofsecond source electrodes 173 b. The voltage transmission lines 172 maybe connected to each other. The voltage transmission lines 172 overlapthe storage region 157 of the semiconductor islands 154 b.

The first and the second drain electrodes 175 a and 175 b are separatedfrom the data lines 171 and the voltage transmission lines 172, and fromeach other. Each pair of the first source electrodes 173 a and the firstdrain electrodes 175 a are disposed opposite each other with respect toa first gate electrode 124 a, and each pair of the second sourceelectrodes 173 b and the second drain electrodes 175 b are disposedopposite each other with respect to a second gate electrode 124 b.

A first gate electrode 124 a, a first source electrode 173 a, and afirst drain electrode 175 a, along with a projection 154 a of asemiconductor stripe 151, form a switching TFT having a channel formedin the projection 154 a disposed between the first source electrode 173a and the first drain electrode 175 a. Meanwhile, a second gateelectrode 124 b, a second source electrode 173 b, and a second drainelectrode 175 b, along with a semiconductor island 154 b, form a drivingTFT having a channel formed in the semiconductor island 154 b disposedbetween the second source electrode 173 b and the second drain electrode175 b.

The data conductors 171, 172, 175 a, and 175 b preferably have firstlayers 171 p, 172 p, 175 ap and 175 bp, second layers 171 q, 172 q, 175aq and 175 bq, and third layers 171 r, 172 r, 175 ar and 175 br. Thefirst layers 171 p, 172 p, 175 aq, and 175 bq and third layers 171 r,172 r, 175 ar, and 175 br are respectively disposed at lower and uppersides of the second layers 171 q, 172 q, 175 aq, and 175 bq. The firstlayers 171 p, 172 p, 175 ap, and 175 bp and the third layers 171 r, 172r, 175 ar, and 175 br are made of a molybdenum alloy (Mo-alloy), whichis composed of molybdenum (Mo) and at least one of niobium (Nb),vanadium (V), and titanium (Ti). Here, the first layers 171 p, 172 p,175 ap, and 175 bp and the third layers 171 r, 172 r, 175 ar, and 175 brof Mo-alloy may include 0.1 to 10 at % of the additives Nb, V, and Ti.It is preferable that the first layers 171 p, 172 p, 175 ap, and 175 bpand the third layers 171 r, 172 r, 175 ar, and 175 br include 3 to 8 at% of the additives. When the content of the additives is increased,adhesiveness to other layers and chemical resistance of the first layers171 p, 172 p, 175 ap, and 175 bp and the third layers 171 r, 172 r, 175ar, and 175 br is improved but resistivity of the first layers 171 p,172 p, 175 ap, and 175 bp and the third layers 171 r, 172 r, 175 ar, and175 br increases. Accordingly, the content of the additives has theabove-described preferable range.

A Mo-alloy, containing a predetermined amount of Nb, V, or Ti which makean isomorphous solid solution with Mo, has better chemical resistance(slow etch speed) and less difference of chemical resistance with thelower layer of Al or Al alloy than Mo itself. As the difference ofchemical resistance between the first and the third layers 171 p, 172 p,175 ap, and 175 bp and 171 r, 172 r, 175 ar, and 175 br and the secondlayers 171 q, 172 q, 175 aq, and 175 bq is reduced, undercut, overhang,and mouse bites, which may arise in an etching process, are prevented.

Like the gate conductors 121 and 124 b, the data conductors 171, 172,175 a, and 175 b have tapered lateral sides relative to the surface ofthe substrate 110, and the inclination angles thereof range from about30-80 degrees.

The ohmic contacts 161, 163 b, 165 b, and 165 b are interposed onlybetween the underlying semiconductor stripes 151 and islands 154 b andthe overlying data conductors 171, 172, 175 a, and 175 b thereon, andreduce the contact resistance therebetween. The semiconductor stripes151 include a plurality of exposed portions that are not covered withthe data conductors 171, 172, 175 a, and 175 b.

Most of the semiconductor stripe 151 is narrower than the data line 171,but the width of the semiconductor stripe 151 broadens near a placewhere the semiconductor stripe 151 and the gate line 121 meet each otherin order to prevent disconnection of the data line 171, as mentioned inthe above.

A passivation layer 180 is formed on the data conductors 171, 172, 175a, and 175 b and the exposed portions of the semiconductor stripes 151and islands 154 b. The passivation layer 180 is preferably made of aninorganic material, such as silicon nitride or silicon oxide, aphotosensitive organic material having good planarity, or a lowdielectric insulating material having a dielectric constant lower than4.0, such as a-Si:C:O and a-Si:O:F, formed by plasma enhanced chemicalvapor deposition (PECVD). The passivation layer 180 may include a lowerfilm of inorganic insulator and an upper film of organic insulator.

The passivation layer 180 has a plurality of contact holes 185, 183,181, 182, and 189 exposing portions of the first drain electrode 175 a,a second gate electrode 124 b, the second drain electrode 175 b, and theend portions 125 and 179 of the gate line 121 and the data line 171,respectively.

The contact holes 182 and 189 expose the end portions 125 and 179 of thegate line 121 and the data line 171 to connect them with externaldriving circuits. Anisotropic conductive films are disposed between theoutput terminals of the external driving circuit and the end portions125 and 175 to assist electrical connection and physical adhesion.However, when driving circuits are directly fabricated on the substrate110, contact holes are not formed. When gate driving circuits aredirectly fabricated on the substrate 110 and data driving circuits areformed as separate chips, only contact hole 189 exposing the end portion179 of the data line 171 is formed.

A plurality of pixel electrodes 901, a plurality of connecting members902, and a plurality of contact assistants 906 and 908 are formed on thepassivation layer 180.

The pixel electrodes 901 are connected to the second drain electrodes175 b through the contact holes 185. The connecting member 902 connectsthe first drain electrode 175 a and the second gate electrode 124 bthrough the contact holes 181 and 183. The contact assistants 906 and908 are connected to the end portions 906 and 908 of the gate line 121and the data line 171 through the contact holes 182 and 189,respectively.

The pixel electrode 901, the connecting member 902, and the contactassistants 906 and 908 are made of a transparent conductor such as ITOor IZO.

A partition 803, an auxiliary electrode 272, a plurality of lightemitting members 70, and a common electrode 270 are formed on thepassivation layer 180, and the pixel electrodes 901.

The partition 803 is made of an organic or inorganic insulating materialand forms frames of organic light emitting cells. The partition 803 isformed along boundaries of the pixel electrodes 901 and defines a spacefor filling with an organic light emitting material.

The light emitting member 70 is disposed on the pixel electrode 901 andsurrounded by the partition 803. The light emitting member 70 is made ofone light emitting material that emits red, green, or blue light. Red,green, and blue light emitting members 70 are sequentially andrepeatedly placed.

The auxiliary electrode 272 has substantially the same planar patternwith the partition 803. The auxiliary electrode 272 has contact with thecommon electrode 270 to reduce resistance of the common electrode 270.

The common electrode 270 is formed on the partition 803, the auxiliaryelectrode 272, and the light emitting member 70. The common electrode270 is made of a metal such as Al, which has low resistivity. Thisembodiment illustrates a back emitting OLED. However, when a frontemitting OLED or dual side emitting OLED is considered, the commonelectrode 270 is made of a transparent conductor such as ITO or IZO.

A method of manufacturing the TFT array panel shown in FIGS. 17-21according to an embodiment of the present invention will be nowdescribed in detail with reference to FIGS. 22 to 33B as well as FIGS.17-21.

FIGS. 22, 24, 26, 28, 30, 32, and 34 are layout views of the TFT arraypanel shown in FIGS. 17 to 21 in intermediate steps of a manufacturingmethod according to an embodiment of the present invention;

FIGS. 23A, 23B, and 23C are sectional views of the TFT array panel shownin FIG. 22 taken along the lines XXIIIa-XXIIIa′, XXIIIb-XXIIIb′, andXXIIIc-XXIIIc′. FIGS. 25A, 25B, and 25C are sectional views of the TFTarray panel shown in FIG. 24 taken along the lines XXVa-XXVa′,XXVb-XXVb′, and XXVc-XXVc′. FIGS. 27A, 27B, 27C, and 27D are sectionalviews of the TFT array panel shown in FIG. 26 taken along the linesXXVIIa-XXVIIa′, XXVIIb-XXVIIb′, XXVIIc-XXVIIc′, and XXVIId-XXVIId′.FIGS. 29A, 29B, 29C, and 29D are sectional views of the TFT array panelshown in FIG. 28 taken along the lines XXIXa-XXIXa′, XXIXb-XXIXb′,XXIXc-XXIXc′, and XXIXd-XXIXd′. FIGS. 31A, 31B, 31C, and 31D aresectional views of the TFT array panel shown in FIG. 30 taken along thelines XXXIa-XXXIa′, XXXIb-XXXIb′, XXXIc-XXXIc′, and XXXId-XXXId′. FIGS.33A and 33B are sectional views of the TFT array panel shown in FIG. 32taken along the lines XXXIIIa-XXXIIIa′ and XXXIIIb-XXXIIIb′.

First, as shown in FIGS. 22 to 23C, a gate metal layer is deposited on asubstrate. The metal layer is deposited by a Co-sputtering. Two targetsare installed in a same sputtering chamber for the Co-sputtering. Onetarget is made of Al or Al—Nd. The other target is made of a molybdenumalloy (Mo-alloy), which is composed of molybdenum (Mo) and at least oneof niobium (Nb), vanadium (V), and titanium (Ti). Here, the Al—Nd targetpreferably contains 2 at % of Nd. The Mo-alloy target may include 0.1 to1 Oat % of the additives Nb, V, and Ti, and more preferably includes 3to 8 at % of the additives. When the content of the additives isincreased, adhesiveness to other layers and chemical resistance isimproved, but resistivity increases. Accordingly, the content of theadditives has the above-described preferable range.

The Co-sputtering process is performed as follows.

At first, power is applied to the Al (or Al—Nd) target while no power isapplied to the Mo-alloy target to deposit a lower layer of Al (orAl—Nd). The thickness of the lower layer is preferably 2,500 Å.

Next, power is switched to be applied to the Mo-alloy target and not tobe applied to the Al (or Al—Nd) target to deposit an upper layer.

The upper and lower layers are simultaneously etched to form a pluralityof gate lines 121 having a plurality of first gate electrodes 124 a, aplurality second electrodes 124 b, and storage electrodes 133. Here, theupper and lower layers are preferably etched by an etchant containingphosphoric acid, nitric acid, acetic acid, and deionized water.Precisely, the etchant may include 63% to 70% of phosphoric acid, 4% to8% of nitric acid, 8% to 11% of acetic acid, and deionized water for theresidual quantity. The etchant may include more acetic acid by about 4%to 8%.

Referring to FIGS. 24-25B, after sequential deposition of a gateinsulating layer 140, an intrinsic a-Si layer, and an extrinsic a-Silayer, the extrinsic a-Si layer and the intrinsic a-Si layer arephoto-etched to form a plurality of extrinsic semiconductor stripes 164and a plurality of intrinsic semiconductor stripes 151 and islands 154 bincluding projections 154 a on the gate insulating layer 140. The gateinsulating layer 140 is preferably made of silicon nitride with athickness of about 2,000 Å to about 5,000 Å, and the depositiontemperature is preferably in a range of about 250° C.-500° C.

Referring to FIGS. 26-27D, a first layer of Mo-alloy, a second layer ofAl (or Al-alloy), and a third layer of Mo-alloy are sequentiallydeposited on the extrinsic semiconductor stripes 164 by a Co-sputtering.The first and third layers are made of a molybdenum alloy (Mo-alloy),which is composed of molybdenum (Mo) and at least one of niobium (Nb),vanadium (V), and titanium (Ti). The three layers are etched using aphotoresist (not shown) to form a plurality of data conductors thatincludes a plurality of data lines 171 including first source electrodes173 a, a plurality of voltage transmission lines 172 including secondsource electrodes 173 b, and a plurality of first and second drainelectrodes 175 a and 175 b.

Before or after removing the photoresist, portions of the extrinsicsemiconductor stripes 164, which are not covered with the dataconductors 171, 172, 175 a, and 175 b, are removed by etching tocomplete a plurality of ohmic contact stripes 161 including projections163 a and a plurality of ohmic contact islands 163 b, 165 a, and 165 b,and to expose portions of the intrinsic semiconductor stripes 151 andislands 154 b.

Oxygen plasma treatment may follow thereafter in order to stabilize theexposed surfaces of the semiconductor stripes 151.

Referring to FIGS. 28-29D, a passivation layer 180 is deposited andpatterned to form a plurality of contact holes 189, 185, 183, 181, and182 exposing the first and second drain electrodes 175 a and 175 b, thesecond gate electrodes 124 b, and an end portion 179 of the data line171.

Referring to FIGS. 31A-32D, a plurality of pixel electrodes 901, aplurality of connecting members 902, and contact assistants 906 and 908are formed on the passivation layer 180 with ITO or IZO.

Referring to FIGS. 32-36, a partition 803 and an auxiliary electrode 272are formed by using a single photolithography step.

Finally, a plurality of organic light emitting members 70, preferablyincluding multiple layers, are formed in the openings by deposition orinkjet printing following a masking, and a common electrode 270 issubsequently formed as shown in FIGS. 22-24.

The present embodiment illustrates gate lines 121 and data lines 171both having a Mo containing layer and an Al containing layer. However,it is possible that only one of the gate lines 121 and data lines 171have multi-layers.

TFT array panels according to embodiments of the present invention havesignal lines including a lower layer of an Al containing metal and anupper layer of a molybdenum alloy (Mo-alloy), which is composed ofmolybdenum (Mo) and at least one of niobium (Nb), vanadium (V), andtitanium (Ti). Accordingly, undercut, overhang, and mouse bite, whichmay arise in an etching process, are prevented and TFT array panels thathave signal lines having low resistivity and good contactcharacteristics are provided.

Although preferred embodiments of the present invention have beendescribed in detail hereinabove, it should be clearly understood thatmany variations and/or modifications of the basic inventive conceptsherein taught, which may appear to those skilled in the present art,will still fall within the spirit and scope of the present invention, asdefined in the appended claims.

1. A thin film transistor array panel, comprising: an insulatingsubstrate; a gate line formed on the insulating substrate and having afirst layer of an aluminum (Al) containing metal and a second layer of aMo-alloy comprising molybdenum (Mo) and at least one of niobium (Nb),vanadium (V), and titanium (Ti), the gate line having a gate electrode;a gate insulating layer formed on the gate line; a semiconductor formedon the gate insulating layer; a data line formed on the gate insulatinglayer and the semiconductor, the data line having a source electrode; adrain electrode formed on the gate insulating layer and thesemiconductor, the drain electrode facing the source electrode with apredetermined gap; a passivation layer formed on the data line and thedrain electrode, the passivation layer having a contact hole; and apixel electrode formed on the passivation layer and connected to thedrain electrode through the contact hole.
 2. The thin film transistorarray panel of claim 1, wherein the first layer includes Al—Nd.
 3. Thethin film transistor array panel of claim 1, wherein the data lineincludes a Mo containing metal.